Minimally Invasive Glaucoma Surgery (MIGS)

What is MIGS?

Glaucoma damages the optic nerve and can cause permanent vision loss. Treatment focuses on lowering intraocular pressure (IOP) to reduce the risk of further damage.

For some patients, eye drops or laser treatment provide enough pressure control. When additional pressure lowering is needed, minimally invasive glaucoma surgery - commonly called MIGS - may be considered.

MIGS can lower eye pressure and may reduce the need for glaucoma medicines, but it does not cure glaucoma, reverse optic-nerve damage or restore vision that has already been lost.

MIGS is an umbrella term for several glaucoma procedures that use small incisions, microscopic implants or internal drainage procedures to improve the movement of aqueous fluid out of the eye.

Compared with traditional filtration surgery such as trabeculectomy, many MIGS procedures involve less tissue disruption and may offer a faster recovery. However, the amount of pressure lowering varies between procedures, and MIGS is not necessarily the best option when very low eye pressure is required.

How does MIGS lower eye pressure?

Aqueous humour is the clear fluid produced inside the front of the eye. Eye pressure is influenced by the balance between how much fluid is produced and how easily it drains away.

Different MIGS procedures lower pressure using different pathways:

• Trabecular bypass: a tiny stent creates a route through the trabecular meshwork into Schlemm's canal.
• Canal-based procedures: the natural drainage canal is enlarged or treated from inside the eye to improve outflow.
• Subconjunctival drainage: a small implant creates a new route for fluid to drain under the conjunctiva, forming a filtering bleb.
• Suprachoroidal drainage: selected implants direct fluid into the space between the choroid and sclera, using an alternative natural outflow pathway.

Who may be suitable for MIGS?

Suitability depends on the type and stage of glaucoma and the amount of pressure lowering needed. Your ophthalmologist may consider MIGS if:

• your eye pressure is not adequately controlled with current treatment
• glaucoma medicines are causing side effects or are difficult to use consistently
• you have open-angle glaucoma and are also having cataract surgery
• laser treatment has not provided enough pressure control, where relevant
• a less invasive surgical approach is appropriate for your target pressure and eye anatomy

Some MIGS procedures are mainly used for mild-to-moderate open-angle glaucoma, while others may be considered for more advanced or difficult-to-control disease. Gonioscopy and other glaucoma testing help determine which drainage pathway is suitable.

MIGS and cataract surgery

Several MIGS procedures are commonly performed at the same time as cataract surgery. Combining the procedures can address cataract and glaucoma in one operating session while adding relatively little additional surgery in suitable patients.

Other MIGS and microshunt procedures can be performed without cataract surgery. Your ophthalmologist will recommend the approach based on your glaucoma, lens status and target eye pressure.

MIGS procedures used in Australia

A number of minimally invasive glaucoma procedures are available in Australia. The exact procedures offered by personalEYES should be confirmed with your treating glaucoma specialist.

iStent inject W

Two very small trabecular micro-bypass stents are placed into Schlemm's canal to bypass resistance at the trabecular meshwork. This procedure is commonly combined with cataract surgery in suitable patients with open-angle glaucoma.

iStent Infinite

A trabecular micro-bypass system that uses multiple stents to improve outflow through Schlemm's canal. Suitability and whether it is used as a standalone procedure depend on the glaucoma and current device indication.

Hydrus Microstent

A small intracanalicular scaffold placed in Schlemm's canal. It bypasses the trabecular meshwork and holds open a segment of the canal to improve fluid drainage.

iTrack Ab-Interno Canaloplasty

A microcatheter is passed through Schlemm's canal from inside the eye and used to dilate the canal. No permanent implant is left in the eye.

XEN Gel Stent

A soft gelatin stent creates a new drainage route from the anterior chamber to the subconjunctival space. Because it creates a filtering bleb, its follow-up and risk profile differ from trabecular bypass procedures.

PRESERFLO MicroShunt

A small biocompatible tube creates a controlled drainage pathway from the anterior chamber to the subconjunctival space. It is the current name for the device previously known as the InnFocus MicroShunt.

MINIject

A soft porous implant placed in the suprachoroidal space to help aqueous fluid drain through an alternative outflow pathway. It may be considered for adults with open-angle glaucoma when further pressure reduction is required.